Lift truck

ABSTRACT

This invention relates to a lift truck provided with a load handling device comprising a push-pull attachment having a pushing frame and means adapted to be put into operation according to the tendency of the forward tilting motion of said pushing frame for cancelling parallelism of the pushing frame and a mast, thereby preventing any occurrence of disorder of the load.

United States Patent Shimizu LIFT TRUCK [72] Inventor: Masahiko Shimizu, Chita-ku, Japan [73] Assignee: Kabushiki Kaisha Toyoda Jidoshokki Seisakusho, Kariya, Aichi, Prefecture, Japan [22] Filed: June 12, 1970 [21] App1.No.: 45,868

[52] 11.5. C1 ..214/514, 214/730 [51] Int. Cl ..B60p 1/04, B66f 9/16, B66f 9/19 [58] Field of Search ..214/514, 730, 750, 510, 82

[56] References Cited UNITED STATES PATENTS Kughler ..214/514 [451 May 30, 1972 2,639,051 5/1953 Thomas ..214/514 2,620,936 12/1952 Abbe ..214/514 2,616,578 11/1952 Dunham ...2l4/514 X 3,048,293 8/1962 Cushman ..214/730 Primary Examiner-Albert .I. Makay Atmrney-Wenderoth, Lind & Ponack [5 7] ABSTRACT This invention relates to a lift truck provided with a load handling device comprising a push-pull attachment having a push ing frame and means adapted to be put into operation according to the tendency of the forward tilting motion of said pushing frame for cancelling parallelism ofthe pushing frame and a mast, thereby preventing any occurrence of disorder of the load.

9 Claims, 10 Drawing Figures PATENTEDMAY 3 0 I972 sum 1 or Q A A A Q 8 2 8 9 WI H JHINI N FIG.

FIG. 6

INVENTOR MAS/M11140 SHIM 1m ATTORNEY S PATENTEDHAH I912 3,666,128

SHEET 2 OF 2 M/MMZQ ATTORNEY 5-;

LIFT TRUCK The principal object of the present invention is to provide an improved lift truck, wherein occurrence of disorder of the load during its handling is prevented, and the pallet grasping operation may be readily effected.

The above and other objects of the invention will become further apparent from the following detailed description, reference being made to the accompanying drawings showing preferred embodiments of the invention. In the drawings: FIG. 1 is a side view of a link mechanism of the lift truck according to the present invention; FIG. 2 shows said link mechanism in folded or contracted position; FIG. 3 is an explanatory view of the same when the fork is advanced; FIG. 4 is an explanatory view of the link mechanism in which the pushing frame of the link mechanism is provided with an inclined guide slot; FIGS. 5 and 6 illustrate other embodiments of the invention; FIGS. 7, 8 and 9 are side elevations of other modified embodiments of the invention; and FIG. 10 shows a heretofore known arrangement for explaining the operation of the fork.

Heretofore, in lift trucks, wooden pallets for handling the load articles were employed. Such wooden pallets not only occupy undue space, but also such pallet is weighty. In view of the above, it has been proposed to employ pallets made of cardboard, which are of lighter weight and less expensive and may be readily handled. Owing to employment of such cardboard pallets, a clamp for grasping and pulling such pallets toward the vehicle and a pusher or a push-pull attachment are now provided. The pushing frame in said attachment is moved forwardly and rearwardly on the fork by means of a link mechanism of the pantagraph type adapted for stretching and contraction. In said link mechanism, as shown in FIG. 10 for example, the base end 38 of a link 3 is pivoted to the lower part of the pushing frame 1, and its upper end 3A is slidably mounted the vertical guide slot 2A formed in the upper part of a carriage or guide frame 2, which end 3A is vertically slidable relative to the mast 8 (FIG. 1). The base end 9A of another connecting link 9 is pivoted on the lower part of said carriage 2. Said links 3 and 9 cross at pivot S, the distance between said pivot S and each pivot of connection 9A, 3B, 3A, 9B, i.e. 8 TA, S 38, S 98, S 3A being equal, so that the pushing frame 1 is maintained in parallel with the mast 8 (FIG. 8) during its forward and rearward movement.

The under side of the end portion 6A of the fork 6 is formed with an inclined face as shown in FIG. 10 to facilitate access of the same into the space under the pallet 4. When the under side of the fork 6 is positioned parallel with the floor, the end face 6A of the fork will be placed in a floated position, as shown in FIG. 1. When the pallet 4 is held by the clamp 5 to pull the pushing frame 1, the end 6A of the fork is liable to be bent, abutting against the pallet 4, whereby the latter would be broken or bent, so that the load articles would be thrown into disorder. So, in loading the articles, the carriage 2 is tilted forwardly and the end portion 6A of the fork is placed on the ground. Furthermore, with forward tilting of the mast, the pushing frame 1 will also be tilted. When it is desired to grasp the cardboard pallet 4 under such condition, the upper portion of the pushing frame 1 being positioned in front of the clamp 5, it will abut against the upper portion of the load 7 (FIG. 10), so that it will be difficult to safely and firmly grasp the pallet 4. An attempt to grasp by force will result in putting the load into disorder. This will be unavoidable also in case of unloading. According to this invention, in view of the above, provision is made for cancelling the parallelism of the pushing frame 1 and the mast 8 when the link mechanism is stretched, rearwardly tilting the upper part of the said pushing frame 1 having the guide slot 18 and the carriage 2 having the guide slot 2A which are connected by the link mechanism of the pantagraph type having the crossing links 3 and 9.

In the embodiments of the present invention shown in FIGS. 1 to 7, in lift trucks provided with the push-pull attachment, S -9A=a, S-B=b, S-3A=c, S-9B=d, and itis assumed that a, b, c, and d are equal. As the upper end 98 of the connecting link 9 is engaged with and slides along the inclined guide slot 18 in the upper portion of the pushing frame 1,

when the link mechanism is contracted the pushing frame 1 and the guide frame or carriage 2 are tilted into substantially parallel position. When the clamp 5 is moved forwardly by stretching the link mechanism, the actuating end 98 of the link 9 will be moved from the upper position of the inclined guide slot IB of the pushing frame 1 toward the lower position, as shown in FIG. 4. As the guide slot 18 is inclined rearwardly, during forward movement of the pushing frame 1, differential displacement of the upper end of the guide slot 1B and the lower end thereof will be enlarged, and the link 9 will pull the upper part of the pushing frame 1 toward the mast 8. Consequently, when the actuating end 9B of the link 9 reaches the lowest position of the inclined guide slot 18, the pushing frame I will be tilted rearwardly from toward the mast 8, at an angle substantially equal to an angle of inclination 90 a relative to horizontal plane.

From the above, it will be seen that if the link mechanism is expanded, with the mast 8 held in vertical position, the pallet 4 made of cardboard is gripped by the clamp 5, the pushing frame 1 will be held in the position inclined at an angle of a relative to the load 7 (FIG. I).

In order to firmly grip the cardboard pallet 4 by the clamp 5, even where the mast 8 is frontwardly inclined at an angle of a to bring the end portion 6A of the fork 6 with the under face against the ground, the angle a of inclination of the pushing frame 1 will be offset by the frontward inclination of the mast 8, so that the pushing frame 1 will be put in a plane perpendicular to the horizontal plane. That is, the pushing frame 1 will take a position parallel with the load 7, as shown in FIG. 3.

From the foregoing, it will be seen according to the present invention which is embodied as mentioned above, that in loading the articles, when the clamp 5 is put in the vicinity of the pallet 4 by tilting the mast 8 forwardly, the pushing frame I will be held in parallel with the load 7, so that any risk of producing disorder of the load caused by pressure of the pushing frame upon the top of the load 7 will be prevented. Thus the clamp 5 may fimily grip the pallet. On the otherhand, upon unloading, when the mast 8 is tilted forwardly, the pushing frame 1 will be rearwardly tilted by means of expansion of the link mechanism, whereby any leading movement of the upper portion of the pushing frame 1 will be prevented. Thus, any disorder of the load articles will not occur, so that safe and smooth loading may be effected. Thus, the clamp 5 may firmly grip the pallet. Consequently, the operator will be relieved of severe inspection of control of several parts, and higher control efficiency can be expected.

Although the foregoing description is made in order that the invention may be completely set forth, it is to be understood that the specific terminology is not intended to be restrictive or confining, and that various rearrangements of parts and modifications of parts and modifications of detail may be resorted to without departing from the scope or spirit of the invention as herein claimed.

For instance, the inclined guide slot 1B may be so arranged that the upper portion is parallel with the rear side of the pushing frame 1 and the remaining lower portion 1C is inclined relative to the forward side of the pushing frame 1 as shown in FIG. 5. Said guide slot 18 may be further modified as shown in FIG. 6, in which the inclined portion 1D is formed at the mid portion of the guide slot 1B as shown, the remaining portions of the slot being arranged vertically. The above mentioned modified forms of the guide slot 1B can be applied to the guide slot 1A or 2A (FIG. 7). As shown in FIGS. 8 and 9, instead of providing the rearwardly inclined slot in one of the pushing frame members or the carriage, the length of one of the links from the pivot S to the end which is slidable in one of the slots can be made shorter than the corresponding portion of the other link. For example, the length of the portion d of the link 9 can be made shorter than the length of the portion c of the link 3. In this instance the slots 1A and 2A are not inclined. The effect of making this portion of one of the links shorter is the same as inclining the slots.

What I claim is:

1. In a lift truck having a mast, a push-pull attachment for load handling comprising a carriage vertically movable relative to the mast, a pushing member movable forwardly and rearwardly of said lift truck relative to said carriage, a pantograph mechanism consisting of a pair of scissors links having the same length and being pivoted to each other at a point intermediate of the ends thereof, one of said links having one end pivoted at one of the upper and lower ends of said pushing member and the other of said links having the corresponding other end pivoted at the other of the upper and lower ends of said carriage and the corresponding one end slidably engaged in a slot in the other of the upper and lower ends of said pushing member, at least one of said slots when said pushing member and said carriage are in their vertical positions having the upper end closer to the mast than the lower end, whereby said pushing member at the end of its pushing stroke has the upper end tilted toward the mast.

2. A push-pull attachment as claimed in claim I in which the slots are on the upper ends of the pushing member and the carriage, respectively.

3. A push-pull attachment as claimed in claim 1 in which said one of said slots is straight and is inclined rearwardly relative to the vertical at a predetermined angle, whereby said pushing member at the end of its pushing stroke tilts rearwardly at said predetermined angle.

4. A push-pull attachment as claimed in claim 3 in which said one of said slots is on said pushing member.

5. A push-pull attachment as claimed in claim 3 in which said one of said slots is on said carriage.

6. A push-pull attachment as claimed in claim 1 in which said one of said slots has the lower end bent away from the mast relative to the upper end.

7. A push-pull attachment as claimed in claim I in which said one of said slots has straight vertical upper and lower portions and an inclined intermediate portion connecting the upper and lower portions.

8. In a lift truck having a mast, a push-pull attachment for load handling comprising a carriage vertically movable relative to the mast, a pushing member movable forwardly and rearwardly of said lift truck relative to said carriage, a pantograph mechanism consisting of a pair of scissors links and being pivoted to each other at a point intermediate the ends thereof, one of said links having one end pivoted at one of the upper and lower ends of said pushing member and the other of said links having the corresponding other end pivoted at the other of the upper and lower ends of said carriage and the corresponding one end slidably engaged in a slot in the other of the upper and lower ends of said pushing member, the length of the portion of one of said links from the pivotal connection to the end thereof slidably engaged in a slot is different from the length of the corresponding portion of the other link and the lengths being such that said pushing member at the end of its pushing stroke has the upper end tilted toward the mast.

9. A push-pull attachment as claimed in claim 8 in which the slots are on the upper ends of the pushing member and the carriage, respectively, and the length of the portion of the link having one end in the slot in the pushing member being less than the length of the portion of the link having one end in the slot in the carriage. 

1. In a lift truck having a mast, a push-pull attachment for load handling comprising a carriage vertically movable relative to the mast, a pushing member movable forwardly and rearwardly of said lift truck relative to said carriage, a pantograph mechanism consisting of a pair of scissors links having the same length and being pivoted to each other at a point intermediate of the ends thereof, one of said links having one end pivoted at one of the upper and lower ends of said pushing member and the other of said links having the corresponding other end pivoted at the other of the upper and lower ends of said carriage and the corresponding one end slidably engaged in a slot in the other of the upper and lower ends of said pushing member, at least one of said slots when said pushing member and said carriage are in their vertical positions having the upper end closer to the mast than the lower end, whereby said pushing member at the end of its pushing stroke has the upper end tilted toward the mast.
 2. A push-pull attachment as claimed in claim 1 in which the slots are on the upper ends of the pushing member and the carriage, respectively.
 3. A push-pull attachment as claimed in claim 1 in which said one of said slots is straight and is inclined rearwardly relative to the vertical at a predetermined angle, whereby said pushing member at the end of its pushing stroke tilts rearwardly at said predetermined angle.
 4. A push-pull attachment as claimed in claim 3 in which said one of said slots is on said pushing member.
 5. A push-pull attachment as claimed in claim 3 in which said one of said slots is on said carriage.
 6. A push-pull attachment as claimed in claim 1 in which said one of said slots has the lower end bent away from the mast relative to the upper end.
 7. A push-pull attachment as claimed in claim 1 in which said one of said slots has straight vertical upper and lower portions and an inclined intermediate portion connecting the upper and lower portions.
 8. In a lift truck having a mast, a push-pull Attachment for load handling comprising a carriage vertically movable relative to the mast, a pushing member movable forwardly and rearwardly of said lift truck relative to said carriage, a pantograph mechanism consisting of a pair of scissors links and being pivoted to each other at a point intermediate the ends thereof, one of said links having one end pivoted at one of the upper and lower ends of said pushing member and the other of said links having the corresponding other end pivoted at the other of the upper and lower ends of said carriage and the corresponding one end slidably engaged in a slot in the other of the upper and lower ends of said pushing member, the length of the portion of one of said links from the pivotal connection to the end thereof slidably engaged in a slot is different from the length of the corresponding portion of the other link and the lengths being such that said pushing member at the end of its pushing stroke has the upper end tilted toward the mast.
 9. A push-pull attachment as claimed in claim 8 in which the slots are on the upper ends of the pushing member and the carriage, respectively, and the length of the portion of the link having one end in the slot in the pushing member being less than the length of the portion of the link having one end in the slot in the carriage. 